On August 11, 2017, Data & Society and fifteen individual scholars—including danah boyd, Julia Ticona, and Amanda Lenhart—filed an amicus brief in a pending U.S. Supreme Court case, Carpenter v. United States. The parties were represented by Andrew Selbst of Data & Society, and Marcia Hofmann and Kendra Albert of Zeitgeist Law.

The case implicates the Fourth Amendment’s “third party doctrine,” which states that that people who “voluntarily convey” information to third parties do not have reasonable expectation of privacy. As a result, when police obtain records from a third party, it does not currently implicate Fourth Amendment rights.

Timothy Carpenter was convicted for a string of armed robberies based on cell site location data which placed him in proximity of the armed robberies he was accused of partaking in. The case concerns the legality under the Fourth Amendment of the warrantless search and seizure of Carpenter’s historical cellphone records, which reveal his location and movements over the course of 127 days.

In the brief, we argue that the “third party doctrine” should not apply to cell site location information because cell phones are not meaningfully voluntary in modern society. Cell site location information contains abundant information about people’s lives, and unfettered police access to it poses a threat to privacy rights.

Aided by scholarship and statistics from the Data & Society research team, we provide evidence that the 95% of Americans that have cell phones cannot reasonably be expected to opt out of owning a cell phone to avoid police searches. The research shows that cell phones are:

Necessary to participate in the most basic aspects of social and family life;

Essential public safety infrastructure and personal safety equipment;

Both necessary to find employment, and an important part of workplace infrastructure;

Widely used for commerce and banking;

Key for civic participation;

Key for enabling better health outcomes;

Critical to vulnerable populations; and

Have been recognized as a necessity by the U.S. government in the past.